Magnetic bearing apparatus

DETAILED DESCRIPTION An object of the present invention is to provide a magnetic bearing apparatus which can automatically calculate a new position of the center of gravity even if an addition heavy product is mounted on a rotating member and can be suitably used particularly when the translation motion and the tilt motion concerning the center of gravity of the rotating member are separately controlled.
In order to attain the above described object, the present invention is characterized, in one mode, by comprising first and second radial magnetic bearings each including a plurality of electromagnets for exerting magnetic attraction forces produced by the electromagnets on a rotating member having an axis of rotation along the horizontal direction in two positions spaced apart from each other in the axial direction of the rotating member and respectively supporting the rotating member in the radial direction with clearances with the rotating member, first and second position detecting means for respectively detecting the positions in the radial direction of the rotating member in the two positions in the axial direction of the rotating member, and a control device for adjusting the magnetic attraction forces respectively produced by the electromagnets in the first and second radial magnetic bearings on the basis of output signals of the first and second position detecting means to hold the rotating member in a predetermined position in the radial direction, the control device comprising a magnetic attraction force calculating portion for calculating the magnetic attraction force produced by each of the radial magnetic bearings on the basis of the output signal of each of the position detecting means, a value of a control current supplied to the electromagnets in the radial magnetic bearing, and an attraction force coefficient of the electromagnets in the radial magnetic bearing, and a center-of-gravity position calculating portion for calculating the position of the center of gravity of the rotating member on the basis of comparison of the calculated magnetic attraction forces produced by both the radial magnetic bearings